This invention relates generally to image and video processing, and more particularly to film grain generation for digital video enhancement.
Traditional motion picture film stock emulsions contain silver halide crystals that reduce after the film stock is exposed and processed and cluster to form miniature “grains.” These film grains make up the image on a piece of film stock. Often the clustering of the film grains is not uniform, giving rise to slight variations that are visible in the film. Various cinematographers have commented that film stock produces a more aesthetically pleasing look than digital video, even when very high-resolution digital sensors are used. This aesthetically pleasing look of the film stock results (at least in part) from the randomly occurring, continuously moving high frequency film grain (as compared to the fixed pixel grid of a digital sensor). This “film look” has sometimes been described as being more “creamy and soft” in comparison to the more “harsh” look of digital video.
Compressed or low-quality digital video also suffers from various imperfections and artifacts. Unlike, film grain, these digital imperfections are not aesthetically pleasing and detract from the appearance of the digital video.
It would therefore be desirable to provide a film grain generator that can approximate the appearance of film grain in digital video. The presence of this generated film grain within digital video can provide the digital video with the desired “film look” as well as masking the appearance of unpleasant digital imperfections.